List of free python stuff for developerππ½
If you're looking for all programming tools around python (not just free). Check this page List of python Programming Tools
Locust - A modern load testing framework
An open source load testing tool define user behaviour with Python code, and swarm your system with millions of simultaneous users.
Tag: load-test, testing, stress-test, python
Free self-hosted open source

JetBrains
PyCharm is a Python IDE for data science and web development. It also provides support for various Python web development frameworks, specific template languages, JavaScript, CoffeeScript, TypeScript, HTML/CSS, AngularJS, Node.js, and more.
Tag: IDE, python, data-science
Free community edition